Teens who frequently play video games have larger reward centres in their brains than those who play less often, according to a study published today in the journal Translational Psychiatry.

The researchers analysed MRI scans of more than 150 German teenagers and found frequent game players had a greater volume of left striatal grey matter than irregular gamers.

Associate Professor Murat Yücel, Clinical Neuropsychologist at the Melbourne Neuropsychiatry Centre and the University of Melbourne’s Department of Psychiatry, explains how young brains respond to reward:

The important thing to remember with the sample in this study is it’s a healthy group. There’s no pathology or illness, so the study doesn’t tell us about brain disorder.

What it may be telling us is that there are individual differences in people’s brains that render them more or less likely to be heavy video game players.

More broadly, adolescent behaviour is driven by reward, much more so than with adults. The study found that there’s a difference in the levels of activity in the brain’s ventral striatum – area of the brain that is very reactive to reward – between the heavy gamers and the light gamers.

This isn’t just a video game-specific region of the brain. Some people might generate dopamine by playing video games. Others might get these rewards through eating, gambling, or engaging in social activities.

Are the children with increased activity in the reward centre of their brain more likely to develop various addictions, or does it fluctuate as they move through adolescence?

That’s the question we all want to answer.

The kids in the study were around 14 years of age, which means changes would be occurring to the way their brain connections are made. These connections will set them up for the rest of their life, influencing the way they behave and may influence whether or not they develop disorders.

Levels of dopamine, which is one of the main neurotransmitter drugs released by the brain, also changes in young brains and has a big influence on this wiring of the brain that occurs in adolescence.

By playing rewarding computer games, these kids are influencing the connections their developing brains are making, through the production of dopamine. So they’re reinforcing certain networks in the brain that are very sensitive and reactive to reward. This is likely to influence their behaviour, temperament and personality. But whether that actually goes on to be a problem or a disorder, we don’t yet know. The brain is really amazingly plastic – much more plastic than we used to think – and it can change over time.

If the behaviour of the kids in the study is locked into video gaming, and that’s all they do (if have very few other activities they find rewarding), that’s where a problem might start. But if they play sport, take music lessons, or are involved in other social activities and they play video games, it’s probably not going to be a major problem. Young people need diversity in their reward activities.

How does this study fit into the existing body of research on the way adolescent brains respond to reward?

We’ve been studying the same region of the brain as the authors of this study, in a group of kids aged 12 to 18 years.

We have found this area of the brain changes a lot during this developmental period, particularly in terms of volume and particularly in boys. We think these volumetric changes in male brains relate to how much they engage in rewarding behaviours such as internet gaming, maybe gambling, and so on. So this study is in line with what we’re thinking.

A lot of my research looks at drug addiction. We know anything that increases the dopamigenic activity – any drug or any behaviour that fires up the dopamine system – has the potential to be addictive. And the more you rev the dopamine system, which makes you feel euphoric, the more you dampen the whole system. So the next time you need more of the drug or experience to get the same high. In other words, you develop tolerance.

So with the kids in the study, if they play video games continuously for long periods of time, they’re getting a dopamine release. The pleasure of gaming is really derived through the uncertainties that continuously occur. And over time, the brain might dampen this system down. Then they would need more of it to gain a similar level of pleasure, which is where the addiction might kick in.

But again, that goes back to balance – if the kids are doing other things that are pleasurable, then their brain might not be so vulnerable.

Did the kids in the video game study have these differences in the brain to begin with, or was this a result of the video gaming?

That’s one of the problems with this study – it’s not longitudinal, so you don’t know if the brain differences were there already, and that’s what led to the video gaming, or if video gaming is leading to changes in the brain system.

Our study is one of the few that follows these kids over the adolescent period. So we’re mapping the changes that are occurring.

What’s next for your study?

We’re going to be following these kids for as long as we can. They’re 18 at the moment so they’re at the age where this search for reward will kick in so they might play video games, try drugs and engage in risky behaviour to satisfy these desires.

We’ll be measuring their activity and comparing it with their brains when they were 12 to 16 years of age to ask whether we could have predicted these behaviours early on from their pre-existing brain differences.

We will also look to see how those behaviours changed the developmental trajectory of the brain in different ways. Hopefully, we’ll be able to answers the questions that this video game study has thrown up.